Jan. 20, 1985: This photo of Montana and Clark was shot in the closing moments of their Super Bowl XIX win. I was struck how Montana and Clark seem to bring out the best in each other. In half these photos, they have expressions on their faces like they're kids again. (Fred Larson / The Chronicle)

In ESPN Films' just-released "30 for 30" documentary "Elway to Marino," which chronicles the historic 1983 NFL draft, John Elway's agent, Marvin Demoff, dropped this bombshell: Bill Walsh explored the possibility of trading Joe Montana in a deal that would have sent Elway to San Francisco.

Leading up to the draft, Demoff kept a diary for Elway, who made it clear he would not play for the Baltimore Colts, the owners of the No. 1 pick whose soon-to-be-moved franchise had a dictatorial coach (Frank Kush), a bumbling owner (Robert Irsay) and an 0-8-1 record in 1982.

Elway's stance prompted a host of teams to explore trading for the former Stanford star, whom Walsh had recruited out of high school as the Cardinal's coach before taking the 49ers job in 1979. Twenty days before the draft, Demoff wrote in his diary: "Discussion with Bill Walsh. Would be interested in Elway if he could trade Montana."

Trade Joe Montana?

In the documentary, which aired Tuesday night, Demoff took a stab at Walsh's thinking. He noted the 49ers followed their 1981 Super Bowl title by missing the playoffs in a strike-shortened '82 season.

"In April of '83," Demoff said, "Bill wasn't as excited about anyone at the 49ers as he was before or later."

The conversation prompted Colts general manager Ernie Accorsi to contact the 49ers' coach. In the interim, Walsh had dismissed the idea.

"He said to me, 'I could just never trade him,' " Accorsi said. "I think it was, at that time, he was not through winning championships with Montana yet."

Walsh won two more championships with Montana. And Elway capped his Hall-of-Fame career in Denver with two titles. It's possible Elway could have won even more with the 49ers, but he acknowledged he would have dealt with far more pressure.

"It's crazy to me that was even a thought," Elway said. "To me, it would have been a good fit. I would have loved to have been able to play for (Walsh). But looking back 30 years later, that would have been a tough situation ..."

Thirty years later, the trade talk came as news to Montana, who tweeted Tuesday: "Can't wait to watch 30 for 30 when I get home. Heard I was almost traded for Elway."